Tape head having a support plate with contoured surface

ABSTRACT

A magnetic recording head according to one embodiment comprises a support having a surface with an opening in said surface; at least one head chin comprising a substrate having a plurality of magnetic recording elements, said head chip positioned to protrude through the opening in the surface of the support for read/write access to a magnetic recording tape, a tape bearing surface of the head chip being positioned above the surface of the support, wherein the at least one head chip includes two transducing surfaces separated in a direction parallel to a direction of tape travel over the at least one head chip by a gap and held in fixed relation to one another. Additional embodiments are also presented.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/426,558, filed Jun. 26, 2006, now U.S. Pat. No. 7,382,581, which is acontinuation of U.S. patent application Ser. No. 10/738,385, filed Dec.17, 2003 and now U.S. Pat. No. 7,133,261.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to magnetic tape recording heads, and moreparticularly to a tape recording head with a support plate having acontoured surface to support the recording tape passing over therecording head.

2. Description of the Related Art

In magnetic storage systems, data is read from and written onto magneticrecording media utilizing magnetic transducers commonly referred to asmagnetic heads. Data is written on the magnetic recording media bymoving a magnetic recording head to a position over the media where thedata is to be stored. The magnetic recording head then generates amagnetic field, which encodes the data into the magnetic media. Data isread from the media by similarly positioning the magnetic read head andthen sensing the magnetic field of the magnetic media. Read and writeoperations are independently synchronized with the movement of the mediato ensure that the data can be read from and written to the desiredlocation on the media.

An important and continuing goal in the data storage industry is that ofincreasing the density of data stored on a medium. For tape storagesystems, that goal has lead to increasing the track density on recordingtape, and decreasing the thickness of the magnetic tape medium. However,the development of small footprint, higher performance tape drivesystems has created various problems in the design of a tape headassembly for use in such systems.

In a tape drive system, magnetic tape is moved over the surface of thetape head at high speed. This movement generally entrains a film of airbetween the head and tape. Usually the tape head is designed to minimizethe spacing between the head and the tape. The spacing between themagnetic head and the magnetic tape is crucial so that the recordinggaps of the transducers, which are the source of the magnetic recordingflux, are in intimate or near contact with the tape to effect efficientsignal transfer, and so that the read element, is in intimate or nearcontact with the tape to provide effective coupling of the magneticfield from the tape to the read element. The conventional head contourcomprises a cylindrical or complex shape which is critical inmaintaining the moving tape at the desired spacing from the head. Thecontact, or near contact, spacing is maintained by controlling thecontour shape to “bleed”, or scrape the boundary layer of air carried bythe tape away and into bleed slots before encountering the transducer toprevent, the tape from “flying”, or losing contact with the transducer.

Alternatively, the contour is designed with a small radios and a highwrap angle so that high pressure is exerted on the head while thetension is low. However, the contour of the head roust be such that thepressure exerted by the tape on the transducer is not so high that thesurface of the transducer wears excessively. Heads are often providedwith outriggers on both sides of the head which help support the tapeand reduce head wear, but, more importantly, control the wrap angle ofthe tape with respect to the head. Any change in radius will change thepressure of the tape on the head at the same tape tension.

A flat contour thin film tape recording head for a bi-directional tapedrive has been described in U.S. Pat. No. 5,905,613. The flat contourhead comprises a flat transducing surface on a substrate having a row ofthin film transducers formed on a surface on one side of the substratewhich forms a gap. The substrate with the row of transducers is called a“rowbar substrate”. The transducers are protected by a closure of thesame or similar ceramic as the substrate. For a read-while-writebi-directional head which requires that the read transducer followsbehind the write transducer, two rowbar substrates with closures aremounted in a carrier facing one another. The recording tape overwrapsthe corners of both substrates with an angle sufficient to scrape theair from the surface of the tape and not so large as to allow air toreenter between the tape and the transducing surface after the tapepasses the corner. By scraping the air from the surface of the movingtape, a vacuum forms between the tape and the flat transducing surfaceholding the tape in contact with the transducing surface. At the cornersof the substrates, bending of the recording tape due to the overwrapresults in separation of the tape from the transducing surface for adistance that depends on the wrap angle, the tape thickness and the tapetension. The transducers must be spaced from the corners of thesubstrate at a sufficient distance to allow the vacuum between the tapeand the transducing surface to overcome this separation.

There is an ongoing need for reduced separation of the transducers andthe recording media and of improved control and reliability of thisseparation in order to support constantly increasing data density andspeed requirements of data storage systems. The present inventionprovides an improved recording head to address this need.

SUMMARY OF THE INVENTION

A magnetic recording head according to one embodiment comprises asupport having a surface with an opening in said surface; at least onehead chip comprising a substrate having a plurality of magneticrecording elements, said head chip positioned to protrude through theopening in the surface of the support for read/write access to amagnetic recording tape, a tape bearing surface of the head chip beingpositioned above the surface of the support, wherein the at least onehead chip includes two transducing surfaces separated in a directionparallel to a direction of tape travel over the at least one head chipby a gap and held in fixed relation to one another.

A magnetic recording head according to another embodiment comprises asupport having a contoured surface with an opening in said contouredsurface; and at least one head chip comprising a substrate having aplurality of magnetic recording elements, said head chip positioned toprotrude through the opening in the contoured surface of the support forread/write access to a magnetic recording tape, wherein the head chip ismoveable relative to the support in a direction perpendicular to thedirection of tape motion over the contoured surface.

A method according to another embodiment comprises, using a coarseactuator, moving a support having a contoured surface with an opening insaid contoured surface, wherein at least one head chip comprising asubstrate having a plurality of magnetic recording elements ispositioned to protrude through the opening in the contoured surface ofthe support for read/write access to a magnetic recording tape; andusing a fine actuator, moving the head chip relative to the support in adirection perpendicular to the direction of tape motion over thecontoured surface.

The above as well as additional objects, features, embodiments andadvantages of the present invention will become apparent in thefollowing detailed description.

The above as well as additional objects, features, and advantages of thepresent invention will become apparent in the following detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and advantages of the presentinvention, as well as the preferred mode of use, reference should bemade to the following detailed description read in conjunction with theaccompanying drawings. In the following drawings, like referencenumerals designate like or similar parts throughout the drawings.

FIG. 1 is a perspective illustration, not to scale, of a firstembodiment of a tape recording head of the present, invention.

FIG. 2 is an end view illustration, not to scale, of the embodiment ofthe tape recording head shown in FIG. 1.

FIG. 3 is an end view section, not to scale, of the head chips andcarrier portion of a first embodiment of the tape recording head shownin FIGS. 1 and 2.

FIG. 4 is a simplified diagram of a magnetic tape recorder system usingthe magnetic recording head of the present invention.

FIG. 5 is an end view section, not to scale, of the head chips andearner portion of a second embodiment of the tape recording head.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a perspective view, not to scale, of a first embodiment of thetape recording head 100 of the present invention. FIG. 2 shows an endview, not to scale, of the tape recording head 100. Referring to FIGS. 1and 2, the tape recording head 100 comprises a support plate 102 havinga cylindrical contoured surface 104 with a rectangular opening 106 whichallows head chips 108 to protrude far enough to allow proper head tapecontact for recording. The cylindrical contoured surface 104 has asubstantially rectangular shape. The support plate 102 is fixed bysupports 112 on a base carrier 110 that is rigidly mounted on a coarseactuator 111 so that the support plate 102 and coarse actuator movetogether in a direction perpendicular to the direction of the linearmotion 115 of recording tape 114 (shown in phantom) over recording head100. The head chips 108 comprising rowbar substrates 116 containing amultiplicity of recording transducers are supported on a carrier 118mounted on a fine actuator 119 and are not fixed to the support plate102 to allow low-mass, high bandwidth fine actuation relative to therecording tape 114 as indicated by the arrow 120. Electrical connectioncables 117 connect the transducers on the head chips 108 to theread/write channel of the associated tape drive.

FIG. 3 shows an end view section, not to scale, of the head chips 108and carrier 118 portion of the tape recording head 100 of FIGS. 1 and 2.The head chip 108 is a bi-directional read-while-write head similar totape recording heads described, in U.S. Pat. No. 5,905,613 whichdiscloses a flat, contour linear tape recording head and U.S. Pat. No.5,883,770 which discloses a partial width linear tape recording head.The head chip 108 comprises rowbar substrates 116 of a wear resistantmaterial, such as the substrate ceramic typically used in magnetic diskdrive heads, fixed on a carrier 118 mounted on a fine actuator means119. The ceramic rowbar substrates 116 are provided with transducingsurfaces 302 and a row of transducers on the surfaces of gaps 304.Electrical connection cables 117 connect the transducers to theread/write channel of the associated tape drive. The rows of transducersare protected by closures 308 made of the same or similar ceramic as therowbar substrates 116. The transducing surfaces 302 of the rowbarsubstrates 116 are designed to protrude a distance d above thecylindrical surface 104 of the support plate 102 when assembled in thetape recording head 100 of FIGS. 1 and 2 to allow proper contact withthe recording tape 114. The protrusion distance d of the transducingsurfaces 302 is typically in the range of 5-25 microns. The protrusiondistance d determines the wrap angle h of the tape 114 at the edge ofthe transducing surface 302. Because of the protrusion of thetransducing surfaces above the cylindrical, surface of the supportplate, the tape to usually does not contact the edge of the rectangularopening 106 of the support plate.

The support plate 102 is fabricated to have a cylindrical surface 104having a polished surface finish. If desired, the polished surface mayinclude microgrooves or other surface texture for controlling stickingin humid environments when the tape is at rest. During operation, therecording tape 114 normally flies over the cylindrical surface 104 witha separation or fly height in the range of approximately 1-5 micronsdepending on the tape, tape velocity and radius. A radius R of 33 mm forcylindrical surface 104 was used to give the desired performance for aminimum fly height flat head. However, a radius R in the range of 10-100mm may be used for various recording head designs and applications. Therectangular opening 106 is formed by molding or, alternatively, by asuitable machining process to have dimensions slightly greater than thehead chip 108 dimensions to allow for fine actuation movement of the ahead without interference from the support plate 102. The dimension ofthe support plate in the direction perpendicular to the direction oftape motion is preferably chosen to support the tape over the full rangeof actuation of the tape recording head. The thickness of the supportplate is chosen to be sufficient to provide the desired strength andrigidity. Typically, the support plate 102 is aligned to the head chips108 after the head and actuator are assembled. The support plateposition is controlled to typically +/−2 microns relative to the headchips for proper operation. The support plate is formed of a hardceramic, such as Al—Ti—C, or of a hardened metallic alloy.Alternatively, the support plate may be formed of a metal, ceramic orplastic material coated with a hard wear layer such as, for example,Si—N to provide wear resistance at possible areas of contact with thetape at the tape edges and near the opening 106 in the support plate.The support plate is preferably static dissipative, or conductive andgrounded or held at an appropriate bias potential to avoid electrostaticcharge buildup.

One embodiment of the magnetic recording head 100 of the presentinvention comprises a support plate 102 having a cylindrical contouredsurface 104 with a substantially rectangular opening 106 in the surfaceto allow head chips 108 to protrude. Alternatively, support plateshaving other contoured surfaces may be used. For example, thecylindrical contoured surface 104 having a constant radius of curvatureR in the direction of linear motion 115 of the tape as shown in FIG. 2may be modified to have a smoothly varying radius of curvature in goingfrom the left side to the midpoint and from the midpoint to the rightside of the support plate shown in FIG. 2. A large radius of curvatureat the left edge of the support plate changing to a smaller radius ofcurvature at the midpoint of the support plate and changing back to alarge radius of curvature at the right edge of the support plate wouldbe one of many possibilities that may be advantageous. Slight contouringof the support plate in the direction perpendicular to the direction oflinear motion 115 of the tape relative to the magnetic recording headcan also be used and may be advantageous in improving stability of thetape relative to the recording head. Similarly, alternative shapes ofthe opening 106 may be used to better match the shape of the particularhead chips being used. For example, a circular or substantially circularopening may be appropriate for a circular button-shaped head chipdesign. In the first embodiment, the opening 106 is approximatelycentered in the contoured surface 104 of the support plate 102.Alternatively, the opening may be offset from the center of the supportplate. The contoured surface of the support plate may have shapes otherthan the substantially rectangular shape of the embodiment illustratedin FIG. 1. The contoured surface may, for example, have a square shapeor may be circular or oval in shape in other embodiments.

The embodiment illustrated in FIGS. 1-3 has transducing surfaces 302that are flat and lie in a common plane. Alternatively, the transducingsurfaces 302 of the two rowbar substrates 116 to may be contoured or maybe tilted at a small angle with respect to one another.

Coarse and fine actuation for positioning the magnetic tape recordinghead perpendicular to the direction of tape motion over the head may beimplemented by a number of actuator means known to the art includingamong others electric motor driven lag screws, electromagnetic inductiondrives (voice coil drives) and piezoelectric devices. Electric motordriven lag screw devices and voice coil drives are most suitable for usein coarse actuator devices moving relatively large masses overrelatively long distances. Micro electromagnetic induction drives andpiezoelectric devices are suitable for fine actuator devices movingsmall masses over small distances with high bandwidth performance.

FIG. 5 shows a second embodiment of a tape recording head 500 accordingto the present invention. Tape recording head 500 differs from the taperecording head 100 shown in FIGS. 1-3 in having the support plate 102fixed by supports 512 on the carrier 118 instead of being fixed bysupports 112 on the base carrier 110. Fixing the support plate 102 onthe carrier 118 results in having the support plate 102 and the headchips 108 moving together with movement of the fine actuator 119. In allother respects, the tape recording head 500 of the second embodiment isthe same as the tape recording head 100 of the first embodiment. In thisembodiment the mass of the support plate 102 adds to the total mass thathas to be moved by the fine actuator which to a degree degrades the highfrequency performance of the fine actuation means. However, fixing thesupport plate to the carrier simplifies alignment of the support plateto the head chips.

FIG. 4 illustrates an embodiment of a magnetic tape recorder or tapedrive system 400 incorporating the tape recording head of the presentinvention. A tape drive control unit 402 provides a motor control signalto rotate tape reels 404 and move magnetic tape 406 across theread/write transducer head 401. Read/write channel 408 transmitsread/write signals between the read/write transducer 401 and the controlunit 402. The data is communicated through I/O channel 410 with host412. Lateral positioning of the transducer 401 with respect to the tape406 is accomplished by coarse and fine positioning actuators 414. Thelateral repositioning by a coarse actuator is required to access thevarious tracks of the tape 406 with the transducer 401. A servo systemand fine actuator may be employed for accurate lateral repositioning ofthe transducer 401. An exemplary servo system includes a servo detector416 to detect both the track that the head is currently on and whetherthe head is off center. Control unit 402 indicates the track address ofa desired new track to position error detection controller 418 forrepositioning the head. Servo detector 416 indicates the current trackto position error detection controller 418, and the controller providesa servo position error signal to the coarse actuator of positioningactuators 414 which repositions the transducer 401 to the new track. Theservo system also provides track following signals to the fine actuatorof positioning actuators 414 so that the tracks on tape 406 may beclosely spaced.

While the present invention has been particularly shown and describedwith reference to the preferred embodiments, it will be understood bythose skilled in the art that various changes in form and detail may bemade without departing from the spirit scope and teaching of theinvention. Accordingly, the disclosed invention is to be consideredmerely as illustrative and limited only as specified in the appendedclaims.

1. A magnetic recording head, comprising: a support having a tapebearing surface with an opening in said surface; at least one head chipcomprising a substrate having a plurality of magnetic recordingelements, said head chip positioned to protrude through the opening inthe tape bearing surface of the support for read/write access to amagnetic recording tape, a tape bearing surface of the head chip beingpositioned above the tape bearing surface of the support positionedclosest to the head chip, wherein the at least one head chip includestwo transducing surfaces separated in a direction parallel to adirection of tape travel over the at least one head chip by a gap andheld in fixed relation to one another, wherein the gap includes a void,wherein the head does not rotate relative to the medium.
 2. The magneticrecording head recited in claim 1, wherein the tape bearing surface ofthe support is contoured in the direction of tape motion over thesurface.
 3. The magnetic recording head recited in claim 2, wherein thetape bearing surface of the plate has a semi-cylindrical contour.
 4. Themagnetic recording head recited in claim 1, wherein the opening in thetape bearing surface is approximately centered in said support.
 5. Themagnetic recording head recited in claim 1, wherein the tape bearingsurface of the support has a substantially rectangular shape.
 6. Themagnetic recording head recited in claim 1, wherein the head chip ismoveable relative to the support in a direction perpendicular to thedirection of tape motion over the contoured surface.
 7. The magneticrecording head recited in claim 1, wherein the tape bearing surface ofthe head chip is positioned sufficiently above the tape bearing surfaceof the support that, in use, a tape passing thereacross is lifted fromat least a portion of the tape bearing surface of the support.
 8. Amagnetic recording head, comprising: a support having a contouredsurface with an opening in said contoured surface; and at least one headchip comprising a substrate having a plurality of magnetic recordingelements, said head chip positioned to protrude through the opening inthe contoured surface of the support for read/write access to a magneticrecording tape, wherein the head chip is moveable relative to thesupport, wherein a path of movement of the head chip relative to thesupport is in a direction perpendicular to the direction of tape motionover the contoured surface and is in a direction parallel to a plane ofthe tape adjacent the head chip, wherein the tape bearing surface of thehead chip is positioned beyond the contoured surface of the support in adirection towards the tape passing thereacross.
 9. The magneticrecording head recited in claim 8, wherein the contoured surface of thesupport is contoured in the direction of tape motion over the surface.10. The magnetic recording head recited in claim 9, wherein thecontoured surface of the plate has a semi-cylindrical contour.
 11. Themagnetic recording head recited in claim 8, wherein the opening in thecontoured surface is approximately centered in said support.
 12. Themagnetic recording head recited in claim 8, wherein the contouredsurface of the support has a substantially rectangular shape.
 13. Amagnetic recording head, comprising: a support having a contouredsurface with an opening in said contoured surface; and at least one headchip comprising a substrate having a plurality of magnetic recordingelements, said head chip positioned to protrude through the opening inthe contoured surface of the support for read/write access to a magneticrecording tape, wherein the head chip is moveable relative to thesupport, wherein a path of movement of the head chip relative to thesupport is in a direction perpendicular to the direction of tape motionover the contoured surface and is in a direction parallel to a plane ofthe tape adjacent the head chip, wherein the tape bearing surface of thehead chip is positioned sufficiently above the tape bearing surface ofthe support that, in use, a tape passing thereacross is lifted from atleast a portion of the tape bearing surface of the support.
 14. Amethod, comprising: using a coarse actuator, moving a support having atape bearing surface with an opening in said tape bearing surface,wherein at least one head chip comprising a substrate having a pluralityof magnetic recording elements is positioned to protrude through theopening in the tape bearing surface of the support for read/write accessto a magnetic recording tape; and using a fine actuator, moving the headchip relative to the support in a direction perpendicular to thedirection of tape motion over the tape bearing surface.
 15. The methodrecited in claim 14, wherein the tape bearing surface of the support iscontoured in the direction of tape motion over the surface.
 16. Themethod recited in claim 15, wherein the tape bearing surface of theplate has a semi-cylindrical contour.
 17. The method recited in claim14, wherein the tape bearing surface of the support has a substantiallyrectangular shape.
 18. The method recited in claim 14, wherein the tapebearing surface of the head chip is positioned sufficiently above thetape bearing surface of the support that, in use, a tape passingthereacross is lifted from at least a portion of the tape bearingsurface of the support.
 19. The method in claim 14, further comprising,using a coarse actuator, moving the support and the head chip in adirection perpendicular to the direction of tape motion over the tapebearing surface.